Personal hygienic habits typically include a means for reducing human body odors. These habits include routine bathing or washing of the body, particularly the axilla, and treating the axilla with compositions to retard odor formation, such as antiperspirant compositions.
Antiperspirants are well known in the art, and generally include an astringent material in a suitable carrier. Astringent materials typically used in antiperspirants are metal salts, particularly aluminum and zinc metal complexes. Exemplary metal salts are disclosed in Plechner, Antiperspirants and Deodorants, 2 Cosmetics, Science and Technology, Balsam and Sagarin, 374-400, 1972; herein incorporated by reference.
Antiperspirant compositions can take a number of different forms, each dependent on the ingredients used in addition to the above mentioned astringent metallic salts. The forms include lotions, solid sticks, and creams; the most popular being solid sticks. Gel sticks are one class of such solid stick antiperspirant compositions.
Antiperspirant gel stick compositions are known in the art. These sticks contain a liquid material and gelling agents. The liquid materials typically are water, lower monohydric alcohols, polyhydric alcohols, and mixtures thereof. The gelling agents most often used include fatty acid soaps, and dibenzylidine monosorbitol acetals (hereinafter DBS). See the following exemplary patents related to antiperspirant stick compositions utilizing soap gels: U.S. Pat. Nos. 3,255,082, Barton, issued Jun. 7, 1966; 4,137,306, Rubino, issued Jan. 30, 1979; 4,944,937, McCall, issued Jul. 31, 1990. See the following exemplary patents related to antiperspirant stick compositions utilizing DBS gels: U.S. Pat. Nos. 4,154,816, Roehl et al, issued May 15, 1979; 4,518,582, Schamper et al, issued May 21, 1985; 4,719,102, Randhawa et al, issued Jan. 12, 1988; 4,722,835, Schamper et al, issued Feb. 2, 1988; 4,725,430, Schamper et al, issued Feb. 16, 1988; 4,781,917, Luebbe et al, issued Nov. 1, 1988; 4,816,261, Luebbe et al, issued Mar. 28, 1989; 4,822,602, Sabetelli, issued Apr. 18, 1989; and 5,106,999, Gardlik et al, issued Apr. 21, 1992.
One significant disadvantage of typical antiperspirant gel stick compositions is a tendency to experience problems associated with interaction between the gelling agent and the acidic antiperspirant actives. For example, the antiperspirant active tends to degrade the acetal portion of the DBS gellant. In fact, improving the stability of DBS gels has been the object of many of the DBS patents cited above. This interaction between the gelling agent and the antiperspirant active can result in reduced efficacy of the actives, poor gel formation, and lower gel stability over time of any gel which is formed. The interaction may also cause processing difficulties at the temperatures and holding times typically encountered during manufacturing.
Furthermore, such antiperspirant gel stick compositions may have additional disadvantages. For example, DBS must be dissolved in a polar solvent. Polar solvents, however, tend to contribute to undesirable stick characteristics such as wet, cold and sticky feel on the skin, shrinkage and containment problems due to high volatility, and skin irritation.
Other gelling agents have been utilized for gelling various non-antiperspirant compositions; such as fuels, motor oils, paints, edible oils, and cosmetics. For example, information regarding the use of n-acyl amino acids as gellants are found in the following references: U.S. Pat. No. 3,969,087 issued on Jul. 13, 1976 to Saito et al.; Japanese Patent Application 1-207223, published Aug. 21, 1989; Japanese Patent Application 1-207223 which published Aug. 21, 1989; and Japanese Patent Application 2-180805 which published Jul. 13, 1988.
Furthermore, information regarding the use of 12-hydroxystearic acid as a gelling agent for non-antiperspirant compositions is disclosed in the following references: Japanese Patent Application 2-180805, cited supra; and Japanese Patent Application 2-264707, published Oct. 31, 1990.
As discussed herein, none of these references provide an antiperspirant gel stick composition having the unique combination of desirable characteristics of the composition of the present invention. For example, the combination of gellants which comprise the gelling agent are stable in the presence of the antiperspirant active during manufacturing; i.e., at the required process temperatures for typical process durations. Additionally, the preferred antiperspirant gel stick composition has good aesthetics due to the inclusion of a non-polar, volatile oil effective for improving skin feel. Incorporation of an effective amount of the non-polar, volatile oil is made possible through the inclusion of a small amount of a relatively polar, non-volatile co-solvent.